On Wed, Feb 27, 2019 at 4:54 PM Jason Merrill <ja...@redhat.com> wrote:
>
> Immediately capturing a VLA means we need to create a dependent VLA capture
> type, and not in the context of the lambda op(), since trying to look up the
> instantiation of the op() while we're substituting into the capture list
> would crash. So I force TYPE_CONTEXT and the binding level out to the
> enclosing function before pushtag, avoid adding a TAG_DEFN, and instead
> force the type to be complete in tsubst_lambda_expr.
...or we could delay doing the special VLA handling until its type
becomes non-dependent, which is a lot simpler and less kludgey.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit eb6c46bbc819c27e1730c935248a23e3a6746a9b
Author: Jason Merrill <ja...@redhat.com>
Date: Thu Feb 28 16:10:12 2019 -0500
PR c++/86969 - ICE with constexpr if and recursive generic lambdas.
* class.c, lambda.c, pt.c: Revert earlier change.
* lambda.c (add_capture): Don't special-case capture of dependent
VLA.
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 830ede56af8..f44acfd62b5 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -7246,7 +7246,6 @@ finish_struct (tree t, tree attributes)
error ("trying to finish struct, but kicked out due to previous parse errors");
if (processing_template_decl && at_function_scope_p ()
- && TYPE_CONTEXT (t) == current_function_decl
/* Lambdas are defined by the LAMBDA_EXPR. */
&& !LAMBDA_TYPE_P (t))
add_stmt (build_min (TAG_DEFN, t));
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index c25df2fbc0e..e7f0fda65be 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -479,31 +479,9 @@ static GTY(()) tree max_id;
an array of runtime length. */
static tree
-vla_capture_type (tree array_type, tree lambda)
+vla_capture_type (tree array_type)
{
- tree closure = LAMBDA_EXPR_CLOSURE (lambda);
- tree type = make_class_type (RECORD_TYPE);
- cp_binding_level *slev = current_binding_level;
- if (closure)
- {
- /* If we're already inside the lambda body, force the capture type out
- into the enclosing context, so we don't crash trying to instantiate
- the capture field in tsubst_lambda_expr. We won't have a TAG_DEFN
- from finish_struct in the enclosing context, which we work around in
- tsubst_lambda_expr. */
- TYPE_CONTEXT (type) = TYPE_CONTEXT (closure);
- cp_binding_level *b = current_binding_level;
- for (;; b = b->level_chain)
- if (b->this_entity == closure)
- {
- while (b->this_entity == closure)
- b = b->level_chain;
- break;
- }
- current_binding_level = b;
- }
- type = pushtag (make_anon_name (), type, ts_current);
- current_binding_level = slev;
+ tree type = xref_tag (record_type, make_anon_name (), ts_current, false);
xref_basetypes (type, NULL_TREE);
type = begin_class_definition (type);
if (!ptr_id)
@@ -549,7 +527,7 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,
if (type == error_mark_node)
return error_mark_node;
- if (array_of_runtime_bound_p (type))
+ if (!dependent_type_p (type) && array_of_runtime_bound_p (type))
{
vla = true;
if (!by_reference_p)
@@ -563,7 +541,7 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,
initializer = build_constructor_va (init_list_type_node, 2,
NULL_TREE, build_address (elt),
NULL_TREE, array_type_nelts (type));
- type = vla_capture_type (type, lambda);
+ type = vla_capture_type (type);
}
else if (!dependent_type_p (type)
&& variably_modified_type_p (type, NULL_TREE))
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 673ea8e2258..d678e278078 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -17989,10 +17989,6 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
if (PACK_EXPANSION_P (ofield))
ofield = PACK_EXPANSION_PATTERN (ofield);
tree field = tsubst_decl (ofield, args, complain);
- if (DECL_VLA_CAPTURE_P (ofield))
- /* The type of a VLA capture might not have a TAG_DEFN in the enclosing
- context, so complete it here. */
- complete_type (TREE_TYPE (field));
if (DECL_PACK_P (ofield) && !DECL_NORMAL_CAPTURE_P (ofield))
{
